Automatic telephone system



Aug. 12, 1924.` 1,504,381

` R. G. RICHARDSON AUTQMAT 1'. C TELEPHONE SYSTEM Original Filed Feb. 4, 1918 2 Sheets-Sheet l fnUEz-znl' Email-Lm] E E155? 5cm Aug. 12, 1924. 1Lso481 R. G. RICHARDSON AUTOMATIC TELEPHONE SYSTEM Original Filed Feb. 4. 1918 2 Sheets-Sheet 2 H ffm-neg YFammi-15mg. 12, 1924.

- 'I UNiTEDysTAIEs PATENT OFF-15GB;-

RODNEY C, RICHARDSON, or CHICAGO, ILLINOIsAssICNOQR To AUTOMATICEL-RCTRIC Y COMPANY, or CHICAGO, ILLINoIs-A CORPORATION or ILLINOIS.v

, AUTOMATIC TELEPHONE SYSTEM.

Appiication fried February 4 1918,seria1No. 215,236. Renewed' April 12,1923.

To all whom it mag/concern.:

Beit known that I, RODNEY Gr. RICHARD- SON, a citizen of the United States of America, and resident' of Chicago, Cook County, 5 State of Illinois, have invented certain'new and useful Improvements in Automatic Telephone Systems,.of "which the following is a specification.

My invention relates in general to improvements in systems in which theV connections are extended by the use of'a calling device by a subscriber and without the'interyvention .of an .operatorat the main or central exchange.

More Yspecifically my invention provides Vimproved switching apparatus and circuits for `use in a system of theV above character.

Amongother objects ofmy inventionV isV 'the provision of a more simple and efficient method of operating automatic .switches of the type known as'two-wire. Other features rand the manner of operation willbe point-l -`ed out hereinafter.A In the' drawings, Figs.

land 2`illustrate an established connectionv between Va calling and a called subscriber vin a system which employs switches embodying my invention. 4

Figure 1 showsa substation A of well known type comprising a transmitter 2, receiver 3, calling device CD, having the usual impulse springs 4 and 5, ringer 6, con-V denser 7, and -the switch hook 8 controlling the springs 9, 10 and 11.A

"Associated with the line conductorsv 12 and 18 of the substation A and individual thereto is the line switch C of the well known l rotary type similar to that shown in United States Letters Patent No.` 1,126,727 to Dietl which embodi'escertain features of my in-V` 40 vention andcomprises a line relaylli, a switching relay 15, and a rot-arymagnet 16. The rotary magnet 16S-operates to rotate the wipers 17,18 and 19 over` a numbeiof contacts to which Vare connected thelineand test conductors 'which lead to a nuinberl of so called selector switches, similar Vto that f shown at D, which are of a similar typeand construction to-the selector switch shown in U. S. LettersPatent No. 815,321, grantedi March 13, 1906, to' Keith, Erickson and Erickson, except that the circuits aremodi- Vfied toadapt it for'the well known two-wire control. The said selector D differs also from the selector shown in'rsai'd patent; in certain features relating to myy improved YVmethod of Operation as will be .pointed out.

The selector D comprises mainly a line rrei lay 20, Yswitching relay 21,V slow release re- 4lay 22, slow'series relay 23, 'vertical magnet 24, rotary magnet 25, Aand release' magnet V y k26. The wipers 27 ,'28,`and 29'are controlled through the medium of Vline vrelay720 fand' connector switch similar to thatshownat i The connector switch E' isofa well known type similar to that shown and described 11i U. S. Letters'Pate1it"l\lo.815,176,grant` edjMarchlS, 1996, to Keith, -Erickson and" Erickson except that the circuits have been modied to adapt it totheiwell lfnowntwo-Y wire method ofV control.'V ,Theconnecto'r E comprises amongothervr'detailslthe line ref..l `lay 30, release relay r31, seriesurelay32, busy Vrelay 33, back bridge relay 34ring cut-off relay 35, wiper cut o n relay 36,"ver'ticaln1agi lnet'37, rotary magnet 3,8, privatefmagnet 39,

andrelease magnetAO. The` usual busyy machine is shown at and the ringing geni erator at R, controlled by an interrupterrelay 41; rIhis connector E vis operated'in re-v sponse lto impulsesffrom `the substationv 'to raise the wi ers69, 70' and'71 to? a-de Ysired level and henrotate themtofaset1of contacts which lead to a desired subscribers liney' The substation A` Vand-its associated switch C are similar in all respects to the substation A andthe'switch CV (-'Fig..1)`.

I will'nowtrace'indetail the circuits "and I methodVV of Operation when the subscrib'er- A desires to establish a talkingA connection with another subscriber for instance) Upon Athe removalfofthe receiver at thev Y individual'v switch C,'tog perform a' preliminary trunking operation. YIt willbe undersubstation A, a ycircuit is closed* at-`the Vsprings) andkl() for thexline relay 14 of; the

stood thataswitchv oftlii's character always t stands with its wipersinconnection withtheV trunk line last used bythe calling subscriber,

which trunk may now'v' be 'either idle'or busy.

'The line relay V14 energizes over a circuit'in- Y Y cluding the"linecoiiductors'12 and 13 and i fY , in opposite directions.

. to extend said line conductors to thefwipers 17 and 18, at the'springs 45 and 46; Thevr relay 15 also closes a locking circ-uit for crates to close a circuit from ground through the' springs 52 and 53y -a-n'd through the re.-v lay 22'to battery. y The, relay 22 energizesing through the lower winding of the relayv 15 to battery and the other passing through the interrupter springs of the rotary magnet 16 and through said magnet 16 to battery. The relayl 15 is differentially wound,

that is when current passes through bothV of its windings, t-lie armatures will not'be attracted, ydue to the windings being wound Therefore if the trunk upon whose test conductor the wiper 19 is resting, is busy, aground will be found thereat and the relay 15 will therefore revmain in its normal position. T lie ground from the private wiper will however cause the operation of the rotary magnet 16 over i the circuit traced, and said magnet will operate as a buzzer to rotate thewipers 17, 18 and 1 9 to the next set of contacts', which is in turn tested by the privatewiper. If this next set of contacts is lousy, the same cycle of operations will occur and the rotary magvnet will therefore continue to rotate the wipers until an idle trunk line is reached(V Then an' idle trunk line is reached there willvbe no ground on the contact which the f Y private wiper 19 engages and therefore' no circuit will be closed for the rotary magnet 16 or for the lower winding o-f the relay 15. The relayV 15 will therefore attract its ar matures, due to the fact that the current.

flowing in the upper winding is not opposed, to disconnect the line relay 14 and ground G2 from the line conductors 12 and 13 'and itself which extends from the wiper 19 through springsf43 and 47 to its upper winding'. VThe relay 14 being slow acting maintains the circuit for the upper winding of relay 15 closed vat springs 42 until the selector 'D has time to operate and supply ground to the Vholding circuit above traced.

Assoo'nlas the switchingrelay 15 extends V'the line conductors toV the'wipers 17 and 18 and therefore to the conductors'leading to the selector D, a circuit is established for the line relay 20 of said selector 'which extends from'ground througlithe lower winding ofV said relay, springs 48 and 49, Vwiper 18, to

and through the substationA and back to the wiper 17, springs 50 and 51, and through the upper Winding of relay 20 to battery. Relay 20 eneigizes over this circuit and opto supply ground to the holding circuit of Vsprings 59 and 61.

the relay 15 of line switch at springs 54 and also prepares a circuit for the switch-V ing relay 21and the rotary magnetV 25 atV This circuit VmayV .beVV traced from ground through springs 54,V

the saine springs.

springs 55, "to a point 56, where the circuit divides, Vone branch extending through the lower winding of relay 21 and another rthrough the rotary off-normal springs y57v and theupper winding of said' relay, whereV the two branches meet and extend to the normally open spring contact 58. Another branch of the aboveCircuitextends from theV point 56, through the V'springs 57 andthe'ro, tary magnet 25 and its interruptor springs to the saine spring @The operation of relay 22 also'prepares a. circuitforV the ver.-V Y' i tical magnet v24 and series relay V23 at springs 59 and 60 and opens one point in the circuit of the release magnetV at The subscriber nowV operates hiscalling device VCD to separatethe springs 4 and 5 c a number of times corresponding to the first digit of the called subscribersnumber. The separation of the 4springs 4 and5 causesthe line relay 2O to be deenergized a correspondand 'slow relay 23 a corresponding'number of times. It'will be Vunderstood that the relay 22, beingV slow acting, maintainsitsarits circuit beine o aened ats rines 52 'and 53.

D f D The circuit. of the vertical magnet extendsy ing lnumber of times toV thereby close 4and open f the circuity of the vertical magnet 24 mature attracted during impulses in spite of froniground through springs 52 and 62,", springs 63, springs 59 and y60, and through relay 23 `and vertical magnet- 24 to battery. i

The vertical magnet 24 operates in iesp'onseY to. these impulses to raisethe V.wipers 27, 28`VV and 29 to a desired level of the contacts which' lead to connector switches Exwhich 'Y have access tothe Vdesiredy group Vof lines; VAs

soon asthefswitch `D .taltesits Ylirst ,vertical`r Y f tactV withv the Vsprings 58 andlifV The step, the spring/64 is allowedto'makeconclosure of springs 64andf65 closes atene pointl the circuit of release magnet 26, which circuit is maintained opeirat the springs 59 and 61of relay 22. VTliefclosure Vof springs 64 and 58 closes another Vpointin theV circuit Vof the rotary magnet: 25 land also ofrel'a'y The slow relay 23energizes'in series Y withfthe vertical magnet, VVremains' in enerV gized position throughout the sending'of the impulses for the first digit4 and tliereforef niaintainsfthe two last mentioned circuits of relay 21 and magnet25open at springs 55.

As soon as the impulses for this kfirst digit cease, the line relay 2O comes to rest energized, thereby maintaining the relay22f energized and opening the circuit of relay 23 for a. length of time sufficient to cause the deenergization thereof. Relay V23,*upon deenergizmg, again closes the springs 55 to ing of relay 21. have no chance to attract its armature. The

' of relay 21.

' above traced holding'circuit.

. AS soon as relay 21 energized to lswitch cause an initial operation of the rotary vmagnet 25 over a circuit from ground through springs 54,v springs 55, springs 57, rotary vmagnet 25 and its interrupter springs, and through springs 58 and 64: to battery. The

magnet 25 thereupon operatesto rotate the wipers 27, 28 and 29 onto the first set of contacts leading to connector (similar to It will be noticed that a circuit for the two windings of relay 21 in multiple was'also closed `at this time by'springs 55. The relay 21, however, is constructed in the same manner as the relay 15 ofv line switch C and therefore doesnot attract its armatures at this time; as soon as the wipers take their `first rotary step, however, the rotary offnormal springs 57 are opened, thereby breaking the initial operating circuit of the rotary magnet and also the circuit of the upper winding of relay 21.

Further operation of the selector now de- YVpends upon the busy or idle conditionV of the various test contacts of the trunk lines over which the wiper 29 passes. If the associated trunk line is busy thewipefr 29 will find a ground' potential present at said contact from an occupying switch (not shown) while vsuch potential willbe absent if the line is idle. Y

Assuming the first trunk line of thelevel to be busy, then as soon as wiper 29 meetsV said'contact a new circuit will be closed for the rotary magnet and for the upper wind- Relay 21 will therefore circuit extends from ground at wiper `29, springs 66 and 67, and through the rotary magnet 25 and upper winding of relay 21 in multiple to battery through springs 58 andV 64.V The magnet 25 will therefore operate in the manner of a buzzer to advance the wipers 27, 28 and 29 to an idlev trunk line. Then such idletrunk line is reached,

it will be clear that no circuit is'closed for the rotarymagnet or for the upper winding The relay 21 will therefore energize through the medium of its lower "winding to switch the incoming line conductors over to the wipers 27 and 28 and disconnect the line relay 20- therefrom. The relav 21, upon energizing, opens the Ycircuit of the rotary magnet at springs 66 and 67 to prevent further rotation and close a loclting circuit for itself from the private wiper Y 29nthrough springs 66 and 68 and through its lower winding to battery, and also opens another point vin the release circuit at springs G8. T he relay 22 maintains the" circuit for the lowerV winding yof relay 21 closed fora short interval after its circuit is opened by relay 20 to give the switch aheadv time topperate to supply ground to the the line-conductors through, acircuit was kcause the line and private wipers to connect cl osed-for the yline relay '30 of connector switch E extending vfrom ground through the lower winding of relay SOto wiper 2 8, thence to vand through the line circuit of` substation A and `back through the other -ing circuit for the relay 21 also entendsV through the springs of relay 23 andto the holding circuit of relay 15 of switch C, from which ground .is disconnected at springs 54 when relay22 deenergizes. The switches C and D therefore are heldv up by the single ground from the Springs ofrelay 31 at'the connector. rPhe line relay 30 is, thereupon,controlled in the usualfwell known manner to first raise the wipers 69,-

70Y and 71 to a desiredflevel through the mediumofv the vertical magnet VE37-in response to one digit; to then allow the side."

switchto pass to second position by'l means of relay 32 andfprivate magnet 39; and'ito then, in response to the last digit, control the rotary magnet 38. in asimilar manner to with the particular setof'fcontactsr desired,

whichin this case leadl tothe substation A.

and its individual switchC.` Y Assuming the called line to be idle *whenl connection is made therewith, the sideswitch wipers will immediately passito third position .and relay 86-will be energized to connect the interrupted generator circuit withr theY called line Yto signal thecalled subscriber. -Another result ofthe side switch passing to third-position is the. closure ofV a circuit for the upper winding of the switching relay 15 of theline-'switch` C from vground through side switch wipei1 72, (in third position) wiperv71, and through the upper winding of said relay'to battery. The mechanical operation of Ythe line. and :cutoff relays 15 and 14" ofthe line switches C and C is similar to that ofthe line and cut-off relays of the 'line switch shown linl,l

U. s. Letters vPatent .ri-051,186,471, 'granted J une 6, 19.16, to John Erickson, that is, the relay 15 cannot fully attract its, armatures unless theV relay lil has first been fenergized. Se that when a call vis made to the line of substation A and a circuit is closed for a winding of relay 15', its armatures will be attracted only'far enough to disconnectlthe linerelay 14" and ground from the calledc line, but .not far enough to connect thei'line'1 through to the calling wipers of'V said switch.

As soon as the called subscriber hears h'is signal, he removes his receiver from the hook and closes a circuit for the ringvcutofi'l relay 35 of the connector which locks up and connects the called subscribers line to the incoming talking circuit through condensers 73 and 74 and also to the baclr bridge battery supply relay 34. Conversation may then be carried on over the heavy conductors shown in the drawing.

f If the called line had been busy when connection was extended thereto, the connector E would have been locked in second position by the ground on the private or test contact and busy tone from the busy machine M would be supplied to the calling man. The ground is extended from private wiper 71, through the side switch wiper 72 (in second position) and through the busy relay 33 and private magnet 39 to battery.

I'Vhen conversation is completed, the connection may be released by the hanging up of the receiver at the calling substation, thereby opening the circuit of the line relay 30 of the connector switch E (Fig. 2). The relay 8O upon deenergizing, opens the circuit of slow relay 31 at the front contact of its springs and closes a point in the circuit of the release magnet 40 at the back contact of said springs. The. relay 31, upon deenergizing, closes the circuit of release niagnet 4@ to release the switch E and also opens the holding circuit for the switching relays 21 and 15 of selector'switch D and line switch C 1). Relay 21, upon deenergizing, closes a circuit at springs 63 for the release magnet Q6 to release the switch Din the usual manner, and relay 15, upon deenergizing, restores the circuit of the line relay 14 to the control of the substation A in readiness f'or the next call.

It will thus be seen that I have provided an improved type of line and selector switches in which a differential relay is used in place of the usual switching relay which has been in the past short circuited during the rotation of the line and selector switches, and I have also provided a very simple and highly efficient method of controlling said differential relays to control the operation of a switch.

Having fully described and ascertained the 'features of my invention. what I cony.

sider to be new and desire to have protected by Letters Patent will be pointed out in the appended claims.

lVliat I claim as my invention is:

l. In a telephone system, an automatic switch, a rotary magnet for said switch, a differential relay therefor, a circuit for said rotary magnet controlled by said differential relay, means for closing a circuit for said differential relay and said rotary mag.-V

net to start the operation of said switch, means for substituting a second circuit for said differential relay and said rotary magnet to continue the operation of said switch, said differential relay adapted to remain deeneigized during the operation of said switch, and means for energizing said differential relay to open said last mentioned circuit when the operation is completed.`

2.111 a telephonesystem, trunk lines ar-V ranged in groups, an automatic switch controlable over a calling line to select oneof said trunk groups and an idle trunk in the selected group, a differentially wound switching relay for extending the callingline to the selected trunk after the switch has operated, circuits for the two windings ofsaid relay one of which serves toprenr vent theenergization of said relay during the trunk selecting movement, and means Joirclosing said circuits when the group se;- lecting operation is completed.V V

3. In a telephone system, trunk lines arranged in groups, anautomatic switch controllable over a callingvline to select onerof said trunk groups rand an idle trunk in the selected group, a differentially wound switching relay f'or extendingthe calling line to the selected trunk 'after the switch;v

has operated, circuits for the two windings of said relay Vthe second of which prevents the said relay from energizing, means for closing said circuits when the groupselect ingl operation is completed, and means for substituting a test circuit for the said second circuit after the trunk selectingniovement is started, whereby the said relay is caused to energize when an idle trunk line is selected. 1

ings, means for energizing onewinding of said relay when the line is called, and means for energizing both windings when the line is calling'and the switch is operated.

5.In a telephone system, a subscribers Yioo individual line or trunk selectingrswitch,Y

means for operating said switch when a callV is made to extend said line to an idle trunk line, a combination cut-off' and switching ro lay in said switch having a holding winding, means for energizing said windng when the line is calling or beingV called, and another winding differentially connected to prevent said relay from energizing while the switch is operating to select an idleV trunk line. l

G. In a telephone system, a subscrihers individual line or trunk selecting switch, a

combinati/onJ cut-off and switching relay in said switch, a line relay normally connected to `the line, means `for energizing said 4coinbiiiation relaytocut-off said line relay when the line is called, means for energizing said Vcombination relay to` extend said line to an lay for connecting said wipers, means for si-V multaneously closing two opposed 'circuits for said relay and a circuit for said magnet to start the operation of the switch, means actuated upon the initial movement of the wipers Ifor opening the second circuit of said relay, and another circuit for said re'- lay including said test wiper, said last men tioned circuit being effective after the second circuit is opened to prevent therelay from energizing until an idle trunk line is found. j 'Y S. In a telephone system, an automatic switch, line and test wipersfor said switch, trunk lines accessible to said wipers, a niagnet for moving said Wipers over contacts of -said trunk lines, a differential switching relay for connecting said wipers, means for closing two opposed circuits for said relay and an initial energizing -circuit for'sa-id magnet to start the 'advance of the wipers of said switch to select an idle trunk line, means actuated upon the initial movement of the wipers foropening the magnet circuit and one circuit ofsaid relay, and other circuits completed by way of said test wiper when the last mentioned circuits are opened for continuing the operation of said magnet and for preventing said relay from energizing until an idle trunk line is found.

9. In a telephone system, an automatic switch, a line relay for said switch, a switching relay forl disconnecting said line relay, vertical and rotarymagnets for said switch controlled by said line and switching relays, means for first operating said line relay to operate said vertical magnet, an auxiliary relay energized during` the operation of the vertical magnet and deenergized aftersaid operation to close a circuit for said rotary magnet and two opposed circuits for said switching relay, said switching relay adapted to remain inoperative upon closure of its circuits, and said rotary magnet adapted to operate iii response to the closure of its circuit-to operate said switch, and means controlled by said rotary magnet for opening one circuit of said switching relay, whereupon said switching relay is energized by means of its other circuit.

10. In a telephone system, a line termivnatiiig in an automaticswitch, trunkV lines accessibleto said switch, means for operating said switch Vto 'automatically select an idleA one of said trunkkk lines, a differentially wound switching relay forextending said line to the selected' trunk line after the switch has operated, VVan energizing 'circuit' for said relay including onewinding thereV of, a second circuitl including'the other winding of' said relay` for preventing the relay from energizing, oft' normal contacts for opening the said second circuit at the beginning of the trunk selecting operation, aV

test wiper for said switch, and a tliirdcircuit including said test Vwiper :for shuiiting the break in said second circuit to prevent said relay from energizing until an idle trunk line lis found.V Y Y 1l. In a telephone system, a line termi- Y'natiiig in an automatic switch,y trunk lines accessible to said switch, means for operating said switch to automatically select an idle one of said trunk lines, a differentially wound switching relay for extending said line to the selected trunk line after VVthe switch has operated, an energizing circuit for said relay includingone winding thereof, a second circuit including the other winding of said relay for preventing the relay from energizing, meansv for opening the said second circuit at the beginning of the trunk selecting o-peration and for maintaining it open during the continuation thereof, and atest circuit substituted for said second circuit when the same is opened in order to prevent the said relay from energizing while the switch is passing'over busy trunk lines.

12. In a trunk hunting switch for automatic telephone systems, incoming and outgoing release trunk conductors normally connected together, the outgoing release trunk conductor terminating in a test wiper of said switch, a .differential wiper switch-y ing lrelay having two windingsnormally connected toi'said conductors, respectively, means for breaking the connection between Ysaid conductors when the hunting move-V ment starts, means for again connecting said conductors effective only when the hunting movement is finished, andV means `for disconnecting the outgoing release trunk conductor from the associated relay winding when'thelast mentioned connection is established.

13. In a ,trunk hunting switch for automatic telephone systems, incoming and outgoing release trunk. conductors normally connected together, the Voutgoing release trunk conductor terminating in a test wiper of said switch,V a differentialv wiper switch` ing relay having two windings normally connected'to said conductors, respectively, Y means for giving said `switch a directive movement preliminary to its hunting moveing one release trunk conductor from its ment, means Ifoi1 opening the incoming reassociated relay Winding When the last men- 10 lease conductor during the directive movetioned connection is established. Y

ment, means forbieaking the connection he- Signed by me at San Antonio, Bexar tween said conductors when the hunting County, Texas, this 26th day of January, movement starts, means for again conneet- 1918. y

ing said conductors when the hunting movement is finished, and means for disconnect- RODNEY G.' RICHARDSON. 

